package history

import (
	"context"
	"fmt"
)

// ListAfter returns up to limit messages for sessionID strictly newer than after
// (created_at > after) in oldest-first order, for forward incremental catch-up: a
// client that reconnected passes the newest createdAt it has already seen and pulls
// only what it missed, however many messages that is (the "before" cursor only walks
// backwards and cannot recover a gap larger than one page). When platform is non-empty
// the page is further restricted to messages carrying that source platform, exactly as
// in List. rowid breaks created_at ties so messages written in the same millisecond
// keep their insertion order. The returned slice is non-nil; limit is clamped to
// [1, maxPageLimit].
func (s *Store) ListAfter(ctx context.Context, sessionID string, after int64, limit int, platform string) ([]Message, error) {
	limit = clampLimit(limit)
	query := `SELECT id, session_id, role, content, mode, mood, image, thinking, platform, device_id, sender_name, adapter_id, created_at
		FROM chat_messages WHERE session_id = ? AND created_at > ?`
	args := []any{sessionID, after}
	if platform != "" {
		query += ` AND platform = ?`
		args = append(args, platform)
	}
	query += ` ORDER BY created_at ASC, rowid ASC LIMIT ?`
	args = append(args, limit)

	rows, err := s.db.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("history: list after %s: %w", sessionID, err)
	}
	defer func() { _ = rows.Close() }()

	msgs := make([]Message, 0)
	for rows.Next() {
		m, err := scanMessage(rows)
		if err != nil {
			return nil, fmt.Errorf("history: scan list after %s: %w", sessionID, err)
		}
		msgs = append(msgs, m)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("history: iterate list after %s: %w", sessionID, err)
	}
	return msgs, nil
}